1. Field of the Invention
The present invention concerns a vacuum arc vapor deposition device for forming thin films on a substrate by means of vacuum arc vapor deposition belonging to physical vapor deposition (PVD) and, more in particular, it relates to device of reactive arc ion plating capable of forming a thin insulative film.
2. Description of the Prior Art
The vacuum arc vapor deposition process and apparatus in the prior art are disclosed in, for example, Japanese Patent Publication Sho 58-3033. FIG. 6 shows a typical embodiment of the apparatus in which the inside of a vacuum chamber (a) is evacuated to a degree of lower than 10.sup.-3 Torr and vacuum arc discharging is started under the evacuated state between a cathode (c) connected to the negative pole of an arc power supply (b) and an anode (d) disposed at the periphery thereof and connected to the positive pole of the power supply by a spark supply device (e), etc. by which arc spots move around at a high speed on the evaporation surface of the evaporation source metal such as Ti on the cathode, thereby evaporating and ionizing the evaporation source metal by the energy of arc spots and vapor depositing to form a film toward a substrate (f) in the vacuum chamber.
When a reactive gas is introduced into the vacuum chamber, reactive vacuum arc vapor deposition in which a compound with the evaporation metal is vapor deposited into a film can also be conducted.
As the anode (d), an electrode disposed so as to surround a substrate in a vacuum chamber may be connected to a positive pole of a power supply and utilized as the anode as shown in FIG. 1 of Japanese Patent Publication Sho 52-14690 in addition to the deposition at the periphery of the cathode.
In this technique, thin films of various metal compounds can be formed on a substrate by selecting the combination of the metal material as the evaporation source on the cathode and the kind of the reactive gas.
The kind of films of metal compounds to be formed on the metal substrate due to the reactive vacuum arc vapor deposition technique as described above may include those conductive material such as TiN, ZrN, HfN, TiC, Ti(C,N), CrN and CrC, as well as insulative materials such as AlN or oxide, for example TiO.sub.2, ZrO.sub.2, HfO.sub.2, V.sub.2 O.sub.5, Al.sub.2 O.sub.3 and mixed oxide, for example, (Ti, Zr)O.sub.2.
In the case of forming such insulative films by the device in the prior art, the insulative films are gradually deposited not only to the surface of the substrate but also to the surface of the anode to hinder the electroconduction in the anode surface, making it impossible to maintain the arc discharge. Accordingly, there has been a drawback in the prior art that the insulative film can not be formed stably.